Usually, in an automatic sheet enclosing and sealing apparatus, information processed by a computer is printed continuously on a continuous sheet and, thereafter, the continuous sheet is conveyed to a cutter unit and the upper and lower edge portions and the left and right edge portions of the single sheets are cut by means of longitudinal and transverse knives so as to provide a single sheet and, thereafter, the single sheet is conveyed to a subsequent unit.
A prior art cutter unit 1 will now be explained with reference to FIG. 1. The unit 1 comprises a continuous sheet conveying system 3 for conveying a continuous sheet 2 having printed thereon various information by a printer unit (not shown in the drawing) and being folded alternately along transverse perforations or being wound into a roll toward a subsequent unit, a cutting system 4 for cutting the continuous sheet 2 conveyed by the continuous sheet conveying system 3, and a single sheet conveying system 6 for conveying a single sheet 5 being cut by the cutting system 4 into the single sheet to a subsequent unit.
The continuous sheet conveying system 3 is also known as a tractor unit and acts to convey the continuous sheet 2 in the vertical directions of the sheet. The conveying system 3 conveys intermittently the continuous sheet 2 by pawls (not shown in the drawing) engaging with feeding holes 7 provided in opposite side portions of the continuous sheet 2. The location of the pawl is adjustable in a direction perpendicular to the feeding direction or the left and right direction so as to match the widthwise dimension of the continuous sheet 2. Displacement and adjustment of the pawl are usually performed manually, but in some recent and expensive apparatus, the width of the continuous sheet is detected and, the location of the pawl is adjusted automatically.
The cutting system 4 is constituted of a transverse knife and longitudinal knives for cutting the upper and lower portions and the left and right portions of the continuous sheet 2. The longitudinal knives for cutting the left and right edge portions 2a and 2b from the continuous sheet 2 so as to make a printing portion having the width W at the central printing portion of the continuous sheet is constituted of combined knives 8 consisting of respective two discs called slitters and arranged along two upper and lower shafts. The transverse knife 9 for cutting the upper and lower portions to make the single sheet having the length L is constituted of two combined blades 9a and 9b of a guillotine type.
The slitters 8 are directly driven by a motor 10 which rotates continuously and acts to cut off the left and right edge portions of the continuous sheet 2 being supplied by a tractor so as to form a predetermined width W of the single sheet. Since the predetermined width W may vary, the slitters can be adjusted manually so as to displace the location along the two upper and lower mounting shafts.
The transverse knife 9 consisting of two combined blades of the guillotine type acts to cut off the top and bottom portions of the continuous sheet 2 with the widthwise dimension being defined by the slitter 8 so as to form the single sheet 5 of a predetermined dimension. The transverse knife 9 acts to cut the continuous sheet 2 between a fixed blade 9b and a movable blade 9a being driven vertically by a cam 12 which is driven by a power source such as an electric motor 10 through an electromotive clutch 11. The cutting operation of the transverse knife 9 is performed at the stopping cycle between the conveying cycles of a tractor unit 3 which convey the continuous sheet 2 intermittently. Thus, the distance of the convey of the tractor unit is equal to the vertical distance L of the single sheet 5 being cut. The single sheet conveying system 6 consists of conveying rollers 14 which convey the single sheet 5 being cut by the cutting system 4 from the cutter unit 1 to a convey guide 13 of a subsequent unit. The single sheet 5 conveyed on the convey guide 13 of the subsequent unit has the width dimension W defined by the slitter 8, and the position of the sheet 5 is restricted by the slitter 8. Usually, in the sheet enclosing and sealing apparatus, a number of functional units are combined to perform a desired integrated function, thus, the mechanical positional relationship between subsequent units is very important in such apparatus. The conveying rollers 14 are driven by a motor rotating continuously except in an error condition, and the single sheet 5 being cut is instantly conveyed to a predetermined position of a subsequent unit. The motor for rotating the conveying roller may be the motor 10 for driving the slitters 8.
In the apparatus, the width W of the single sheet 5 being cut and the positional relationship between the single sheet 5 and the conveying guide 13 of the subsequent unit are determined simultaneously by adjusting the position of the left and right slitters 8. Namely, in adjusting the position of the left and right slitters 8, it is important to satisfy simultaneously these two requirements, or the widthwise dimension of the single sheet being cut and the positional relationship of the single sheet being conveyed. Thus, it is very difficult and time consuming to adjust the position of the slitters. Further, any automatic adjusting means utilizing such as a motor and the like have not been available and the slitters 8 are very sharp cutting edges, and the adjusting operation is very dangerous since the operator is required to perform the positional adjustment manually.